CLINICAL AND BACTERIOLOGICAL EPIDEMIOLOGY OF EXTENDED-SPECTRUM BETA-LACTAMASE-PRODUCING STRAINS OF KLEBSIELLA-PNEUMONIAE IN A MEDICAL INTENSIVE-CARE UNIT

The epidemiology of extended-spectrum p-lactamase (ESBL)-producing str ains of Klebsiella pneumoniae was studied over a 16-month period in a medical intensive care unit (ICU), A control program involving enhance d isolation procedures, surveillance cultures at admission and then at 1-week intervals, and selective digestive decontamination (SDD) was i nstituted. Phenotypic and genotypic markers (plasmid content and DNA m acrorestriction polymorphism determined by pulsed-field gel electropho resis) were used to compare 138 strains of ESBL-producing K. pneumonia e, The incidence of colonization and/or infection with ESBL producers was 11.9%. ESBL-producing K. pneumoniae strains were isolated from 64 of 65 patients. Fifty-five cases were considered acquired in the ICU, while nine cases were imported. Forty-five infections occurred in 32 p atients; 20 infections involved the urinary tract. SDD failed to reduc e the incidence of acquisition of ESBL-producing K. pneumoniae. Combin ed use of markers was necessary to achieve accurate differentiation of strains. A single epidemic clone (SHV-4 beta-lactamase-producing K, p neumoniae) was the cause of 85% of the ICU-acquired cases. Sporadic oc currence of SHV-5, TEM-3, SHV-2, and SHV-3 producers accounted only fo r a few cases.